NOTE: The 2007-2011 JKs use different battery clamps than the later models. But there's much more to this post than just that story. Owners of later models--or even non-Jeep owners (shame on you!), may find info that is useful below.

Been doing some upgrades to the battery system in my 2007 JKU. I have the Benchmark Designs dual-battery kit installed (this company is no longer in business). The start battery was having problems, but, honestly, the entire system could really use some cleaning up. Bear in mind that I also have an sPOD with the 80-ampere cable upgrade, and two Blue Sea four line fuse blocks on my overhead comm rack that distribute juice to the three radios mounted to it (only one is ever used at a time since all three use the same antenna NMO mount). Two fuse blocks are used because there is one for the positive and one for the negative power lines (more on that at the bottom of this post).

Anyway, while replacing the bad start battery, wanted to repair/upgrade any of the cabling, battery mounting hardware, remove inline fuses as much as practical, and move negative wires off the battery terminals that weren't OEM or needed for the dual-battery system. Again, more on the why of that down below. I also had a problem with my Cole Hersee battery isolator that I wanted to check out after the new battery was installed: It would leave the two batteries connected up until voltage fell below 12.8 volts. It's supposed to disconnect at 13.2 volts.

The first thing of note is the lousy battery clamps that the 2007-11 JKs were manufactured with. What I was not aware of until I started this is that the positive battery clamp has an unusually small post for the attached wires. I had bought some marine cable clamps from my local auto parts store, but they would not work. I tried three different brands--AutoZone, O'Reilly's and Napa. None had this odd size. Searching online, the only thing I could find was a $50 battery terminal set from Q-Tec, on sale for $40, which I just received an e-mail for today on sale for $30. If all you have is a single battery and you want to attach a few mod accessories to it, this is actually a pretty good solution. Recommend you take a look at it. But I wasn't happy with that. I wanted to use a simpler marine terminal for a cleaner install.


OEM positive battery terminal. Note the color of the red cable to the lower left. It used to be bright red and smaller, just like the others. I cut open the heat shrink and the individual strands of wire were covered with green corrosion. Time for a new cable.


Note the orange colored rubber washer that is dry rotted (part of the Benchmark Designs dual-battery mod). Another sample of some of the old, worn materials that I would repair.

So, here is what I did ...


First I built the replacement red cable. I have stock I keep of battery terminals and the special, measured solder beads to use with them.


After inserting the solder into the terminal, I heated it up with a blow torch--took about 15 seconds--then inserted the cut and trimmed 2 Ga cable into the hole. BTW, the 2 Ga wire has slightly thicker insulation than what came with the Benchmark Designs kit or the OEM hardware. I like this: The possibility of a battery cable wearing though to contact ground scares the crap out of me.


Once the work piece cooled down enough, I added a piece of heat shrink over it, then blasted it with a heat gun. The heat shrink I use has a sealer in it that bubbles out slightly to form a weather resistant seal. So do all of the smaller terminal lugs I use.


The new cable vs the older cable.


Next, I needed to resize the holes in the OEM hardware that would be attached to the start battery positive terminal. Again, on the 2007-11 JKs, these are smaller than standard size. So, I used a Dremel grinding stone to enlarge it about a sixteenth of an inch. There were two terminal lugs I did this to. I used care doing this: I didn't want the wire to get tangled up on the rotating tool and spin around, especially since one has a fusible link.


I then installed the new hardware.


Of particular note is this Blue Sea fuse block that attaches directly to the battery terminal of my aux battery. It's a nice solution to inline fuses.


A close-up of the start battery positive terminal with the modified OEM wiring and the one new cable from Benchmark Designs attached. This is a slightly too small negative battery terminal attached to a positive post. They are different sizes. But lead being malleable, I was able to reshape it to fit tightly. In a few weeks I'll pull it off and see that all surfaces remain bright and shiny. Any hint otherwise, and I'll be installing a Q-Tec battery terminal.


Aux battery negative post. Note the three ground terminations on the engine bay sheet metal across the bottom of the photo. I moved several negative wires that were attached to the aux battery ground post to two of those lugs. I did leave two non-OEM/non-Benchmark Designs wires attached to the aux battery negative post: One for the winch and one for the comm rack. That latter has an inline fuse just out of sight. Again, I'll explain that below.


Finally, note the black rubber washers for the battery hold-down J-bolts, some new high temp split cable loom and the use of Adel clamps to hold a couple cables in place. The Adel clamps are probably not really needed, but I keep a few of those handy so used them.

Now I had the batteries installed, all new battery terminals, several inline fuses removed and some new wire loom and cable clamps. I checked the Cole Hersey dual-battery isolator and it still held the batteries connected until 12.8 volts was reached--which was typically hours after I had parked the rig for the night. I ordered a new one and replaced it. And now the batteries disconnect moments after I turn off the engine.

Finally, negative wiring and why you should connect it to grounding terminals on the vehicle body or frame and not to your start battery negative terminals: If you lose that heavy gauge wire to ground from your start battery for some reason--let's say it becomes loose and corroded down at the ground connection on the vehicle--then the best ground for cranking your engine to start could be through some aftermarket mod you've installed. Can you imagine running 200 amps through your refrigerator negative wiring? That's a prescription for an electrical fire. Of course, it is often recommended to connect radio gear direct to the battery terminals to reduce the chance of electromagnetic interference (EMI). Thus, just in case that negative battery wire should become a high-resistance route, you have a fuse in the negative wire to the radio that will blow. Your rig won't start, but at least it won't be on fire. I did consider if the winch negative cable would serve as a suitable alternative, but you're depending on a good ground through the painted/powdercoated surfaces of however that bumper is attached.

 

Note: I exceeded the character limit in the above post, but here are a couple more URLs that may come in handy:

Blue Sea Four Line Fuse Blocks

sPOD 80 amp cable upgrade

 

that looked like a great project for sure. good way to clean up wires, replace cables, and overall ensure the batteries and elec. system is up to par.